gan·gli·on 
(găngglē-ən)
(găngglē-ən)n. pl. gan·gli·a (-glē-ə) or gan·gli·ons
1. A group of nerve cells forming a nerve center, especially one located outside the brain or spinal cord.
2. Medicine A benign cystic lesion resembling a tumor, occurring in a tendon sheath or joint capsule.
3. A center of power, activity, or energy.
[From Greek, cystlike tumor, nerve bundle.]
gan′gli·onic (-ŏnĭk) adj.